The photochemical dechlorinations of chlorides of the benzene, naphthalene, and biphenyl series are compared. It is concluded that triplet-state homolysis of the Ar-Cl bond is the preferred reaction pathway provided that the chloro compound has a triplet energy close to the necessary bond-dissociation energy. For 1-chloronaphthalene this is not the case, and an inefficient degradation takes place from the singlet state.
